Heat exchangers are commonly employed apparatuses for exchanging heat from one medium to another, such as from one fluid to another fluid, from fluid to a gas or from a gas to a fluid. A common type of heat exchanger employs a plurality of lengths of parallel tubes through which one fluid circulates, the tubes being normally confined in an enclosure with provisions for flowage of fluid past the tubes and externally of them. In this way liquid passes concurrently through all of the tubes and the fluid with which heat is to be exchanged, such as air, passes externally of the tubes. Normally, a header is provided at each end of the paralleled tubes to connect the ends of the tubes to a common enclosure by which one fluid is conveyed to and from the heat exchanger.
Heat exchangers are frequently employed in the aircraft industry. The typical commercial passenger transport plane has many heat exchangers, such as for maintaining lubricant within a preselected temperature range, for heating and cooling the interior of the aircraft and so forth. While aircraft heat exchangers work in the same fundamental way as the heat exchangers for any other industrial or building application, aircraft heat exchangers are subjected to increased stress due to acceleration, such as when the aircraft is taking off or landing, and to a high degree of vibration. Acceleration and vibration are not typically a problem with most heat exchanger applications, such as heat exchangers used in residential or commercial air conditioning. For this reason, aircraft heat exchangers have posed special problems and additional attention must be paid in the design and manufacture of aircraft heat exchangers to combat the combined stress of acceleration and vibration.
In the typical heat exchanger that includes a multiplicity of spaced apart tubes, it is important that the tubes be supported with relationship to each other between the headers affixed to each end of the tubes. This is particularly true in aircraft heat exchangers since vibration and acceleration can cause movement of the tubes if not properly supported, resulting in failure of the heat exchanger. This disclosure is directed to an improved stiffener plate for use in heat exchangers, particularly of the type employed in the aircraft industry, although the invention is not limited to aircraft heat exchangers.
For reference to others who have provided heat exchanger designs applicable for aircraft industry and particularly for stiffener plates, reference may be had to the following previously issued U.S. Pats. Nos.: 2,488,627; 3,245,465; 4,054,355; 4,070,751; 4,131,332; 4,150,556; 4,191,040; 4,234,041; 4,381,135; 4,647,086; 4,634,208; 4,635,711; 4,653,779; 4,699,403; 4,890,867; 4,924,586; 4,940,263; and 4,958,757.